Tool for milling insulated wires



Jan. 14, 1930. R. M. MARTENS 1,743,826

TOOL FOR MILLING INSULATED WIRES Filed March 28, 1929 27.067710 21 ado Za/1 777. fiiaz'hifis Patented Jan. 14, 1930 UNITED STATES rnasze RUDOLPHM. MARTENS, OF WEST ROXIBUBY, MASSACHUSETTS TOOL FOR MTLLINGTNSULATEDW'IRES Application filed March 28, 1929. Serial No. 350,571.

This invention relates to means for preparing insulated wire for makingconnections such as splicing to other wires, or to binding posts ofelectric devices, or wherever conducting connections are to be made, andthe invention has particular reference to means for milling away fromthe end of an insulated electric wire ,as much of the insulation as maybe desired or is necessary in order to bare any length of the wirerequired- The method heretofore most commonly em ployed to remove someof the insulation from a wire has been to use a knife blade to cut andpare the insulation in a manner similar to whittling a stick. This is aslow and tedious operation. Another practice has been to employ a devicehaving rotary sharp-edged jaws which first make an annular cut in theinsulation at a predetermined distance from the end of-the wire, andthen move the wire or the jaws in a longitudinal direction to cause thejaws to exert a pulling action on the insulation. This, owing to thevery adhesive characteristics of the insulation, is impractical Figure 1is a side elevation illustrating my invention in a preferred embodimentthereof.

Figure 2 is a sectional View of the most essential portions of the tool,on a larger scale than Figure 1, and illustrating a piece of wire beingoperated upon.

Fig. 3 is an end view of a portion of the device, looking from the leftin Fig. 1.

Fig. 4 is a section on line 14 of Fig. 2.

Fig 5 is a section on line 55 of Fig. 2.

Fig. 6 is a section on line 66 of Fig. 2.

The frame 12 is preferably of such form and construction that the toolcan be firmly secured in some convenient place for use, as

by the employment of a'clamp gripping the base of the frame to thelowered tail board of a work truck, or to any suitable bench or shelf.The frame has bearings 13 for a shaft 14: whichat one end has a wheel 15and crank handle 16 for the manual operation of the shaft. Sometimes,however, it may be desirable to connect a motor to the shaft. Said shaftis tubular or hollow throughout its length and preferably has transverseapertures 17 and scale marks, the object of which will be presentlyexplained.

The other end of the shaft from the wheel 15 is interiorly enlarged asillustrated at 18 in Figure 2 to receive the tubular shank 19 of thetubular twist auger 20 the cutting edges 21 of which face or arepresented to operate in a plane substantially perpendicular to the axisof the shaft. Suitable means are provided to enable the auger and itsshank to be removably locked to the shaft, the means illustratedcomprising a locking pin 22 carried by one end of a spring 23 secured tothe shaft at 24, said pin extending through a hole in the shaft andentering a groove 25 in the shank of the auger. The inner end of thetubular shank 19 is somewhat flattened as illustrated by Figure 6, orotherwise made of irregular form, to fit a corresponding shape of theinner end of the enlargement in the shaft, to ensure rotation of theauger with the tubular shaft when the shank of the tool is locked inplace by the pin 22 and the shaft is rotated. The structure justdescribed enables the auger to be removed or re-set, when it is de- 35sired to sharpen the edges 21 of the tool or to change one tool foranother. I have found in practice that three different sizes of twistangers will suffice for all the usual purposes, such three differingonly as to the diameters 0 of their central bores to permit the passagethrough or into the tubular tool of the bared ends of the wire, andalso. differing as to the radial lengths of the cutting edges 21. Thestructure and mounting of the members just described enables one tool tobe quickly substituted for another.

Surrounding the auger is a wire-guiding member which also guards theusers fingers from being injured, said member being removably mounted inposition for use, its removability being to enable the tool to beremoved. Said member comprises a sleeve portion 26 fitting the outerendof the shaft 14 and having an internal annular groove 27- The shaft 14has an external annular groove 28 and a split spring ring 29 fitspartially into both of'the grooves 27, 28 and serves to hold the outermember on the shaft and yet permits the shaft to rotate during theoperation presently described without transmitting rotary motion to theouter member. If a decided outward pull is exerted on said outer member,the spring ring 29 will yield sufliciently into one or the other of theannular grooves to enable the outer member to be separated from theshaft when access to the tool is desired for the purpose of removing thelatter to sharpen it or substitute another therefor.

l wo arms 30 extend from the sleeve 26 and carry the guide ring 31 whichhas a central hole 32 the outer end of which is preferably somewhatenlarged or tapered for a purpose presently explained.

In operation, the end of a piece of insulated wire such as illustratedat the left end of Fig- 7 me 2 is pushed into the guiding hole 32 andthe shaft and anger are then rapidly rotated. The guiding member 26, 31,does not rotate but as inward pushing of the wire continues, theinsulation is cutaway by the edges 21 and escapes through the openingsbetween the arms 30 while the bared wire passes into and through theauger and as far into the tubular shaft as desired. The tool 20 being aclosed twist auger, it serves to clean the wire core during operation.The holes 17 in the shaft enable the user to estimate the length of wirethat has been bared by the auger. Owing to the fact that the shaft istubular its entire length, any length of insulated wire may be bared. Itis to be understood however that I do not limit myself to suchstructure, as said shaft need not be tubular for more than a part of itsentire length.

During the pushing ofthewire into the tubular auger and the rotation ofthe latter, the insulation is cut into particles by the edges 21 of theauger and thrown outthrough the spaces between the arms 30. Wheneversuffioient baring of the wire has been accomplished, it is onlynecessary to pull the wire back and away from the tool. Owing to thefact that the cutting edges 21 of the auger are slightly prolongedbeyond the end of the spiral body of the tool, said edges serve to liftchips the full cross section of the insulation while the ends of thespiral body back from said cutting edges serve to form edges to engagethe wire core. And furthermore the two radially opposed cutting edges 21assist in centering the flexible (wire) core.

During the use of the tool, the member which surrounds the auger servesthree purposes; viz: its taper-entrance hole or opening 32 firstproperly directs the end of the wire that is to be operated upon toaccurate position relatively to the end of the tool; said hole thenguides and steadies the wire as it travels along; and the member as awhole guards the hands of the user from contact with the revolving augerwithin it.

Having now described my invention, I claim:

1. A tool for removing insulation from flexible wires, comprising arotary tubular shaft having a tubular twist anger at its end.

2. A tool for removing insulation from flexible wires, comprising arotary tubular shaft having a tubular closed twist auger at its ends,the shaft having openings to enable the operator to see the end of awire therein.

3. A tool for removing insulation from flexible wires, comprising arotary tubular shaft having a tubular twist auger at its end, said augerhaving radially opposed cutting edges.

at. A tool for removing insulation from flexible wires, comprising; arotary tubular shaft having a tubular twist auger at its end,

and a ring-shaped guide having a sleeve portion mounted on said shaft inadvance of the auger.

5. A tool for removing insulation from flexible wires, comprising arotary tubular shaft having a tubular closed twist auger at its end, thecutting edges of said auger being slightly prolonged beyond the end ofthe spiral body to lift a chip the full cross section of the insulationwhile the ends of the spiral body back from the cutting edges themselvesform edges to engage the wire core.

In testimony whereof I' have affixed my signature.

RUDOLPH M. MARTENS.

